1. The Field of the Invention
This invention relates to decking for boats or other marine vessels particularly but not exclusively for leisure boats.
Conventional decking for leisure boats comprises sheets of teak secured to a substrate by an adhesive. Teak decking is expensive and not favoured environmentally due to deforestation of natural timber resources. Other species of wood have inferior engineering properties. A problem with natural teak decking has been a limitation on the ability to withstand modern cleaning techniques, such as washing using high pressure water jets.
It is an object of the present invention to provide decking having superior engineering and maintenance properties particularly resistance to washing using high pressure water jets.
According to a first aspect of the present invention decking comprises:                a support selected from the group consisting of: polymeric materials; marine engineering polymers, fibre reinforced polymers, polymer metal composites, metal or wood sheets or marine superstructure;        an array of strips of polymer treated wood secured to the support by means of an adhesive;        wherein the polymer treated wood comprises a wood species selected from the group consisting of: maple species impregnated with a wood compatible polymerisable monomer, preferably selected from furfuryl alcohol, bis hydroxymethyl furan and mixtures thereof and subsequently dried and cured.        
Preferably the treated wood exhibits a hardness value of 3 to 8 on the Brinell scale. The hardness is important for wear resistance in use of the decking. Alternatively or in addition, the treated wood exhibits an average bending modulus of rupture (MOR) of between about 100 and about 130 MPa. Preferably the treated wood exhibits one of: an average bending modulus of rupture (MOR) of between about 100 and about 130 MPa or a hardness value of 3 to 8 on the Brinell scale.
The bending modulus of elasticity (MOE) may be between 10000 and 16000 MPa in comparison to typical values of 13400 MPa for teak and 8000 MPa for untreated maple. The preferred monomer is furfuryl alcohol.
The average bending modulus of rupture (MOR) is preferably between about 120 to about 130 MPa.
Alternatively or in addition to the MOR value, the wood strips exhibit a hardness value from about 3 to about 8, preferably from about 4 to about 7, more preferably from about 5 to about 6 on the Brinell scale.
The hardness of natural teak is about 3.5 and the MOR of teak is about 148 MPa.
The adhesive is preferably being selected from the group consisting of: polyurethane adhesives, modified silyl polymer adhesives, epoxy resin adhesive, silicone adhesives and other adhesives developed for use in exterior marine constructions.
The support of the decking of this invention may comprise a substrate layer or sheet of polymeric or other material. The substrate may be selected from: polyester sheeting, glassfibre, reinforced polyester, epoxy-wood composites, plywood, polyaramid (Kevlar) sheet, carbonfibre composites or laminates, and solid wood or metal sheets, e.g. steel or aluminium. Alternatively the wood strips may be applied directly to a metal, or conventional wooden decking or otherwise to the superstructure of a boat.
Preferred species of wood is selected from the group consisting of the commercially used maple species including:
Acer macrophyllumBigleaf mapleAcer negundoBoxelderAcer nigrumBlack mapleAcer rubrumRed mapleAcer saccharinumSilver mapleAcer saccharumSugar mapleAcer pseudoplatinusSycamore mapleAcer platanoidesNorway mapleAcer campestreField maple
According to a second aspect of the present application a process for manufacture of decking comprises the steps of: assembling a laminate comprising an array of strips of wood secured to a support selected from the group consisting of a sheet of polymeric material selected from the group consisting of marine engineering polymers, fibre reinforced polymers, polymer metal composites metal or wood sheets or superstructure by means of an adhesive selected from the group consisting of: polyurethane adhesives modified silyl polymer adhesives and epoxy resin adhesives; applying heat and pressure to the assembly and allowing the adhesive to cure.
In preferred embodiments edges of the strips of wood include rebates, a sealant material being deposited within the rebates to seal edges between adjacent strips. The sealant material serves to form a tight and flexible seal that allows some shrinking and swelling of the individual wood boards while maintaining the integrity of the deck. The sealant may also serve to improve the non-slip properties of the decking. The rebates may be L-shaped, triangular or rectangular to provide T-shaped, V-shaped or rectangular spaces between adjacent strips.
The support may comprise a polymer material, especially a material selected from polymers used for manufacture of marine engineering components, including polyurethanes, polyamides, polyalkenes and polyesters. Fibre reinforced polymers may be used or polymer metal composites. Metal or wooden sheets may be used as substrates. Alternatively, the decking may be applied directly to marine superstructures to form a decking surface thereon.
Decking in accordance with this invention exhibits numerous advantages. Use of teak is avoided. Maple is cheaper and may be cultivated without depleting natural resources. The engineering properties of decking in accordance with this invention are superior to those of decking manufactured from teak. Surprisingly the visual appearance of decking in accordance with this invention resembles the appearance of natural teak. Furthermore the present inventors were surprised to discover that the appearance of the decking after weathering resembles the appearance of weathered natural teak. The timber surface is brown when new, turning grey on exposure to moisture and UV radiation, providing a similar appearance to weathered teak.
Decking in accordance with this invention may be cleaned using high pressure jet washing apparatus. This allows a jet washer to be used to clean the decking as well as metallic or polymeric parts of a boat. The need for a separate cleaning regime is avoided. Teak decking may be liable to delaminate when repeatedly exposed to a jet washer. Despite the use of maple, decking in accordance with this invention can be handled by boat builders in the same way as teak decking. Indeed the decking of this invention may be more resistant to the conditions encountered during transportation storage and manufacture. Decking in accordance with this invention has better hardness and wear resistance properties than natural teak giving a longer working lifetime.
Decking in accordance with this invention may exhibit a volumetric swelling of 8 to 10% from oven dried to moisture saturated, comparable to a value for teak (Tectonia grandis) of 9%. Untreated samples of maple have a swelling of about 16%.
The density of the impregnated timber composite may be between about 700 and about 1000 kgm−3 in comparison to 630 kgm−3 for teak.
Decking in accordance with this invention may be glued, caulked and surface treated using methods of materials conventionally used in the boat decking manufacture industries. The invention therefore provides a higher performance decking without the need for use of specialist high performance adhesives, hardwoods or specialist methods of manufacture.
The superior engineering properties and resistance to delamination provides a longer lifetime with slower wear and thinning in use. Also the invention may allow use of thinner timber than in manufacture of conventional decking. Less adhesive may be required. The strips may be selected and cut to display an attractive grain of the maple. The superior strength and resistance to delamination allows timber to be cut to optimally display graining without need to control the angle of the grain relative to the working surface of the decking.
Without risking to be bound by theory, it is believed that the bonding of the adhesive to the furan polymer impregnated within the cellular wood structure is superior to the bonding of the adhesive to the cellulose of untreated timber, particularly hardwoods having dense cellular structures or containing lipid components.
2. The Relevant Technology
The polymer treated timber of the present invention may be manufactured as disclosed in EP1341648, EP1368167, WO2004/011216, WO2004/011214, the disclosures of which specifications are incorporated into the present specification for all purposes by reference.